pitchman vs travelling salesman

pitchman

noun
  • A salesman, especially one who aggressively markets wares from a street stall, or a carnival or side show act. 

travelling salesman

noun
  • A man who travels, often within a certain territory, soliciting orders or selling goods. 

How often have the words pitchman and travelling salesman occurred in a corpus of books? (source: Google Ngram Viewer )